BṚHADĀRAṆYAKA UPANISHAD · 1.5.16

अथ त्रयो वाव लोका मनुष्यलोकः पितृलोको देवलोक इति ।
सो ऽयं मनुष्यलोकः पुत्रेणैव जय्यो नान्येन कर्मणा ।
कर्मणा पितृलोकः ।
विद्यया देवलोकः ।
देवलोको वै लोकानां श्रेष्ठः ।
तस्माद् विद्यां प्रशंसन्ति ॥

atha trayo vāva lokā manuṣyalokaḥ pitṛloko devaloka iti ।
so ’yaṃ manuṣyalokaḥ putreṇaiva jayyo nānyena karmaṇā ।
karmaṇā pitṛlokaḥ ।
vidyayā devalokaḥ ।
devaloko vai lokānāṃ śreṣṭhaḥ ।
tasmād vidyāṃ praśaṃsanti ॥

Next there are verily three worlds, the world of men, the world of the Fathers, the world of the Devas. The world of men can be gained by a son only, not by any other work. By sacrifice the world of the Fathers, by knowledge the world of the Devas is gained. The world of the Devas is the best of worlds, therefore they praise knowledge.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)